/* ── Course Hub Styles ── */
.course-hub-hero {
  min-height: 45vh;
  display: flex;
  align-items: center;
  text-align: center;
  padding-top: 100px;
  padding-bottom: 40px;
  position: relative;
  overflow: hidden;
}
.course-hub-hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse at center top, rgba(34,197,94,.12) 0%, transparent 60%);
  pointer-events: none;
}
.course-hub-hero h1 { font-size: clamp(2rem, 5vw, 3.2rem); margin-bottom: 12px; }
.course-hub-hero p { color: var(--muted); max-width: 640px; margin: 0 auto; font-size: 1.05rem; line-height: 1.7; }

/* Module Grid */
.module-grid {
  display: grid;
  gap: 20px;
}
.module-grid.style-rows { grid-template-columns: 1fr; }
.module-grid.style-cards { grid-template-columns: repeat(auto-fill, minmax(340px, 1fr)); }

/* Module Card (row style) */
.module-card {
  display: flex;
  align-items: flex-start;
  gap: 20px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px 28px 28px 20px;
  text-decoration: none;
  color: var(--text);
  transition: border-color .25s, transform .25s, box-shadow .25s;
  position: relative;
  overflow: hidden;
}
.module-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; bottom: 0;
  width: 4px;
  background: var(--accent);
  border-radius: 4px 0 0 4px;
  opacity: 0;
  transition: opacity .25s;
}
.module-card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
  box-shadow: 0 12px 40px rgba(0,0,0,.25);
}
.module-card:hover::before { opacity: 1; }

.module-num {
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--accent);
  min-width: 44px;
  line-height: 1;
  font-family: var(--font-mono);
}
.module-info { flex: 1; }
.module-info h3 { font-size: 1.1rem; margin-bottom: 6px; color: var(--text); }
.module-info p { color: var(--muted); font-size: 0.88rem; line-height: 1.6; margin-bottom: 10px; }
.module-meta { display: flex; gap: 12px; align-items: center; flex-wrap: wrap; }

/* Sub-module links */
.sub-modules {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 8px;
}
.sub-modules a {
  font-size: 0.78rem;
  padding: 4px 10px;
  border-radius: 20px;
  border: 1px solid var(--border);
  color: var(--muted);
  text-decoration: none;
  transition: all .2s;
}
.sub-modules a:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: rgba(34,197,94,.06);
}

/* Lesson page styles */
.lesson-header {
  padding-top: 110px;
  padding-bottom: 32px;
  border-bottom: 1px solid var(--border);
}
.lesson-header .breadcrumb {
  font-size: 0.82rem;
  color: var(--muted);
  margin-bottom: 12px;
}
.lesson-header .breadcrumb a {
  color: var(--accent);
  text-decoration: none;
}
.lesson-header h1 { font-size: clamp(1.6rem, 4vw, 2.4rem); }
.lesson-header .lesson-meta {
  display: flex;
  gap: 16px;
  margin-top: 12px;
  color: var(--muted);
  font-size: 0.85rem;
}

.lesson-content { max-width: 820px; margin: 0 auto; padding: 40px 24px 80px; }
.lesson-content h2 { margin-top: 48px; margin-bottom: 16px; }
.lesson-content h3 { margin-top: 32px; margin-bottom: 12px; }
.lesson-content p { margin-bottom: 16px; }
.lesson-content ul, .lesson-content ol { margin-bottom: 16px; padding-left: 24px; }
.lesson-content li { margin-bottom: 8px; }

/* Lesson navigation */
.lesson-nav {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  padding: 32px 0;
  border-top: 1px solid var(--border);
  margin-top: 48px;
}
.lesson-nav a {
  flex: 1;
  padding: 16px 20px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  text-decoration: none;
  color: var(--text);
  transition: all .2s;
}
.lesson-nav a:hover { border-color: var(--accent); }
.lesson-nav .nav-label { font-size: 0.75rem; color: var(--muted); display: block; margin-bottom: 4px; }
.lesson-nav .nav-title { font-weight: 600; font-size: 0.92rem; }
.lesson-nav .next { text-align: right; }

/* Lesson table of contents sidebar */
.lesson-layout {
  display: grid;
  grid-template-columns: 1fr 220px;
  gap: 40px;
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
}
.lesson-toc {
  position: sticky;
  top: 100px;
  align-self: start;
  font-size: 0.8rem;
}
.lesson-toc h4 { color: var(--muted); font-size: 0.7rem; text-transform: uppercase; letter-spacing: .08em; margin-bottom: 12px; }
.lesson-toc a {
  display: block;
  padding: 4px 0 4px 12px;
  color: var(--muted);
  text-decoration: none;
  border-left: 2px solid var(--border);
  transition: all .2s;
  line-height: 1.5;
}
.lesson-toc a:hover, .lesson-toc a.active {
  color: var(--accent);
  border-color: var(--accent);
}

@media (max-width: 900px) {
  .lesson-layout { grid-template-columns: 1fr; }
  .lesson-toc { display: none; }
}
@media (max-width: 640px) {
  .module-card { flex-direction: column; gap: 8px; padding: 20px; }
  .module-num { font-size: 1.2rem; }
  .sub-modules { gap: 4px; }
}